<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>边框</title>
    <style>
        #d1 {
            width: 200px;
            height: 200px;
            border: 40px dashed red;
            /*设置圆角，值越大越圆，超过宽高一半为正圆(前提时正方形)*/
            border-radius: 50%;
            text-align: center;
            line-height: 200px;
            font-weight: bold;
            font-size: 30px;
        }
        #d2 {
            width: 100px;
            height: 100px;
            border: 1px solid red;
            /*给元素添加内边距会影响元素的显示宽高*/
            padding-left: 50px;
            padding-top: 50px;
        }
    </style>
</head>
<body>
<div id="d2">内边框</div>
<div id="d1">边框测试</div>
</body>
</html>